Seeta and Geeta go for a swim after a gap of every 2 days and every 3 days respectively. If on 1st January both of them went for a swim together, when will they go together next?
Answer & explanation
Answer: (d) 13th January
A gap of 2 days means Seeta swims every 3rd day; a gap of 3 days means Geeta swims every 4th day. They meet again after LCM(3, 4) = 12 days, on 13th January.
- Gap of 2 days: Seeta swims on 1, 4, 7, 10, 13 … January (every 3rd day).
- Gap of 3 days: Geeta swims on 1, 5, 9, 13 … January (every 4th day).
- LCM(3, 4) = 12, so the next common day is 1 + 12 = 13 January.
- Check: 13 is in both lists; 7 is only Seeta's and 12 is neither's.
Remember · 'After a gap of n days' means the event repeats every (n + 1) days; then take the LCM.
Question and answer: UPSC's official GS Paper II (2019, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·